The scriptures don't speak in terms of selflessness vs. self-interest. Instead the scriptures speak of charity vs pride.
Pride = do as I will.
In the end, the will of God is the ultimate expression of both perfect selflessness (help others) and self-interest (peace, joy, and treasures in heaven). Zion satisfies wants and needs of all its members. It really is the greatest feast of fat things.
"And in this mountain shall the Lord of hosts make unto all people a feast of fat things, a feast of wines on the lees, of fat things full of marrow, of wines on the lees well refined." (Old Testament, Isaiah 25:6)